Latching assembly with magnetic locking

ABSTRACT

A latching assembly for a door swingable toward and away from a doorjamb or the like between a closed and an open position, comprising a pair of latch members mounted on the door and jamb, respectively, and relatively movable between an engaged latching position and a disengaged unlatched position. Each latch member includes one or more latching surfaces engageable with a latching surface on the other latch member when in the latched position preventing movement of said door relative to said doorjamb. Permanent magnet holding means is provided for holding or locking said latching members in said latched position, and selectively controlled electromagnetic means is used for producing a magnetic unlocking force with a polarity opposing that of said permanent magnet means for unlocking and relatively moving said latching members out of said latched engagement when said door is to be opened.

1*Jan. 14, 1975 LATCHING ASSEMBLY WITH MAGNETIC LOCKING [75] Inventor:William S. Wang, Marina Del Rey,

Calif.

[73] Assignee: Consolidated Controls Corporation,

Bethel, Conn.

[21] Appl. No.2 225,598

Related U.S. Application Data [63] Continuation of Ser. No. 3,132, Jan.15, 1970, Pat.

[52] U.S. Cl 292/251.5, 292/201 [51] Int. Cl. E05c 19/16 [58] Field ofSearch 292/201, 252, 261, 299,

[56] References Cited UNITED STATES PATENTS 9/1923 Englund 292/15 5/1944Duby 335/290 2/1952 Manting 292/251.5

2,888,290 5/1959 Pierce 292/25l.5 3,312,492 4/1967 Remhof.... 292/2011123,636 3/1953 Mark 292/25l.5 X

Primary Examiner-Richard E. Moore Attorney, Agent, or FirmPhilip C.Peterson [57] ABSTRACT A latching assembly for a door swingable towardand away from a doorjamb or the like between a closed and an openposition, comprising a pair of latch members mounted on the door andjamb, respectively, and relatively movable between an engaged latchingposition and a disengaged unlatched position. Each latch member includesone or more latching surfaces engageable with a latching surface on theother latch member when in the latched position preventing movement ofsaid door relative to said doorjamb. Permanent magnet holding means isprovided for holding or locking said latching members in said latchedposition, and selectively controlled electromagnetic means is used forproducing a magnetic unlocking force with a polarity opposing that ofsaid permanent magnet means for unlocking and relatively moving saidlatching members out of said latched engagement when said door is to beopened.

13 Claims, 13 Drawing Figures PATENTED 1 4MB 3. 860.277

sum 2 OF 2 MW IT :90 18 188 W LATCHING ASSEMBLY WITH MAGNETIC LOCKINGThis is a continuation of application Ser. No. 3,132, filed Jan. 15,1970, now US. Pat. No. 3,658,370, issued Jan. 25, 1972.

The present invention relates to a new and improved magnetic latchingassembly, and more particularly to a latching assembly wherein magneticforces are used to hold or lock a pair of mechanically engageable latchmembers in latched engagement.

The magnetic latching assembly of the present invention is particularlywell suited for application in modern aircraft for latching doors orclosure panels on compartments containing oxygen equipment and masks andother emergency supplies for the passengers. In this specificapplication it is desirable that the latching as sembly be hidden orgenerally unaccessible to the passenger and preferably mounted on theinside of the door or closure member within the compartment whichcontains the oxygen mask. Normally, unlatching is accomplished byelectrical means actuated by the pilot of the aircraft; in addition,however, means must be provided whereby a passenger, with properinstruction, can manually unlatch the latch assembly from outside of thecompartment so that in cases of emergency, when the normal electricalunlatching system fails, the door can be opened and fast access can behad to the emergency oxygen equipment inside the compartment.

The latching assembly of the invention is arranged so that the latchingor holding means, which holds and maintains the door in a closed or shutposition, is not dependent on magnetic force but instead holding forcesare established by a positive mechanical latching engagement between oneor more latching surfaces on a pair of cooperating latch members andthus the latch ing assembly is able to withstand considerable G loading,such as might be caused by rapid aircraft acceleration and decelerationor by other forces, such as prying or hammering on the door by apassenger. The latching assembly of the present invention is normallyunlatched by a controlled electrical impulse delivered at the desirerdtime, and the energy of the impulse may also be used to aid in openingthe door.

The previously described features are objects of the present invention,and it is another object of the invention to provide a new and improveddoor latching assembly in which permanent magnet means is used toprovide a holding or locking force for retaining a pair of latchingmembers in positive mechanical latched engagement.

Another object of the invention is to provide a latching assembly of thecharacter described wherein unlocking of the engaged latch members outof latched position is accomplished by electromagnetic means developinga force in opposition to the holding force of said permanent magnetmeans.

Another object of the present invention is to provide a new and improveddoor latching assembly of the character described using electromagneticforce for unlocking the latch members, which force is also effective toaid in opening the door with which the latching assembly is used.

Another object of the present invention is to provide a new and improvedlatching assembly which is completely hidden within a compartment on theinside of an access door thereof, yet which may be latched or unlatchedfrom outside of the compartment by means of a tool or finger insertedthrough a slot or opening in the door or compartment wall.

Another object of the invention is to provide a new and improvedlatching assembly of the character described including means forvisually indicating when the latching assembly is in an unlatchedposition, even though the door is still closed.

Another object of the invention is to provide a new and improvedlatching assembly of the character described wherein mechanical latchingor holding force is attained with spherical latching surfaces.

Another object of the invention is to provide a new and improvedlatching assembly of the character described wherein one of the latchmembers includes a spheroid mounted adjacent the free outer end of adeflectable support member.

Another object of the invention is to provide a new and improvedlatching assembly described in the preceding object including anopposite latching member comprising socket forming means for receivingsaid spheroid and including a plurality of spheroids therein in annularringlike array for movement radially inwardly and outwardly into and outof latching engagement.

Another object of the invention is to provide a new and improvedlatching assembly of the character described which is reliable andsimple in operation, low in cost, and which can be mass produced involume yet meet stringent safety test requirements.

Briefly, the foregoing and other important objects and advantages of thepresent invention are accomplished by providing a new and improvedlatching assembly having a pair of latch members mounted on a door anddoorjamb, respectively, and movable relatively between an engaged,latched position and disengaged, unlatched position. Permanent magnetholding or locking means is provided for normally maintaining the latchmembers in an engaged latch condition, and electromagnet means isprovided for momentarily opposing and nullifying the magneticholdingforce with a force of opposing polarity for moving the latchmembers to an unlatched position, permitting the door to be opened.

In one embodiment, the latching members comprise a spheroid mountedadjacent the free, outer end of a flexible support rod and the spheroidis movable into and out of engagement with socket forming meanscomprising a plurality of spheroids in annular ringlike array movableradially inward and outward into and out of latching and unlatchedengagement with the spheroid on said flexible rod.

For a better understanding of the present invention, reference should behad to the following detailed description taken in conjunction with theclaims and drawings, in which:

FIG. 1 is a side elevational view of a typical aircraft seat including acompartment mounted in the back portion of the seat for containingemergency oxygen equipment for the passengers on the aircraft;

FIG. 2 is an enlarged fragmentary sectional view taken on a verticalplane through the aircraft seat of FIG. 1 showing the compartment andclosure door thereof in enlarged detail with one embodiment of a doorlatching assembly constructed in accordance with the features of thepresent invention;

FIG. 3 is a sectional view showing the latching assembly as seen in thedirection of arrows 3-3 of FIG. 2;

FIG. 4 is an elevational view of a compartment door on the rear of theaircraft seat;

FIG. 5 is a cross-sectional view taken substantially along line 55 ofFIG. 3;

FIG. 6 is a cross-sectional view similar to FIG. 3 and illustrating atool or implement being extended through an opening in the door formanually unlatching the latching assembly;

FIG. 7 is a view similar to FIG. 6 and illustrating a tool insertedthrough an opening in the door for manually latching the latchingassembly;

FIG. 8 is an enlarged vertical sectional view similar to FIG. 2 showinganother embodiment of a latching assembly constructed in accordance withthe features of the present invention;

FIG. 9 is a rear elevational view of the seat compartment of FIG. 8 asseen in the direction of arrows 99;

FIG. 10 is a fragmentary vertical sectional view similar to FIG. 8 butillustrating the latching assembly in an unlatched position and thecompartment door in a partially open position;

FIG. 11 is a transverse sectional view taken substantially along line11-11 of FIG. 8;

FIG. 12 is a transverse sectional view similar to FIG. 11 takensubstantially along line 1212 of FIG. 10; and

FIG. 13 is a vertical sectional view of yet another embodiment of alatching assembly constructed in accordance with the features of thepresent invention and employing a modified manual unlatching system.

Referring now more particularly to the drwings, in FIG. 1 is illustrateda typical aircraft seat 10 having a base or seat 12 permanently attachedto the floor 14 of an aircraft or other vehicle and an upstanding backportion 16 with an upper head rest 16a. The upstanding back portion 16is pivotally mounted on the seat por-.

tion 12 for angular adjustment to provide for comfort of the passengersin the aircraft. In order to provide oxygen and other equipment for thepassengers in case of an emergency, an enclosure or compartment 26 ismounted in the back portion 16 of the seat 10, and the compartment isadapted to contain an oxygen mask and other necessary emergencyequipment as needed or required. The compartment 26 includes a pair ofvertical sidewalls 11, a bottom wall 13, a rear or back wall 15, and atop wall 17, the forward edge portion 24 of which forms a jamb for adoor 30. The door 30 is normally closed so that the interior of thecompartment 26 is not accessible to the passengers except in anemergency. The door is hinged to the bottom wall 13 of the compartmentand is pivotable from a closed position (solid lines, FIGS. 2, 6, 7, 8,and 13) to an open position (dotted lines FIGS. 1, 2, and 10).

In accordance with the present invention, in FIGS. 2 through 7 isillustrated one embodiment of a new and improved latching mechanism 20comprising a first latching subassembly 22 mounted on the inside surfaceof the compartment top wall 17 adjacent the forward edge or doorjamb 24and a second latching subassembly 28 mounted adjacent the upper edge onthe inside surface of the compartment door 30. The latching subassembly22 includes a base 32 preferably stamped from sheet metal and providedwith several elongated slots 34 for receiving sheet metal screws 38 orother suitable fasteners used for securing the subassembly in place onthe compartment top wall 17. The base includes a pair of upstanding,spaced apart, parallel flanges 40 having circular openings therein toreceive and support the opposite ends of an elongated pivot pin 42 onwhich pin is pivotally mounted a U-shaped latching lever 44.

As viewed in FIGS. 2, 6, and 7, the right-hand leg 44a of the U-shapedlatching lever 44 is supported by the pin 42, and the bight or middleportion or leg 44!) of the lever is movable between a generallyhorizontal, latched position (FIGS. 2 and 6) and an unlatched position(dotted lines in FIG. 2 and in FIG. 7). The lefthand leg 440 of theU-shaped latch lever forms a latching dog adapted to mechanically engagea slot 46a formed adjacent the free outer end of a latch lever 46 of thesecond latching subassembly 28. The latch lever 46 is mounted on a pivotpin 48 carried on a support bracket 50 having a base portion 52 securedto the inside surface of the compartment door 30. The bracket 50includes a pair of upstanding flanges 54 (FIG. 3) through which thepivot pin 48 extends and the latch lever 46 is disposed to pivot betweenthe flanges between a generally horizontal, latched position (FIGS. 2, 6and 7) and a downwardly deflected, unlatched position (dotted lines FIG.2) out of engagement with the latching leg 440 of the latch member 44.The lever 46 is biased to pivot in a clockwise direction (arrow A inFIG. 2) about the pivot pin 48 by a coil spring assembly 56 so that upondisengagement with the latching leg 440 of the U-shaped latch member 44,the lever 46 will automatically pivot to the unlatched position. In thisposition, the free outer end of the lever projects outwardly beyond theouter face of the door 30 (dotted lines FIG. 2) through a keyhole shapedslot 30a (FIG. 4) and provides a visual indication that the latchingmechanism 20 is in the unlatched position (even if the door 30 remainsin the closed or upright position).

In accordance with the present invention, the latch levers 44 and 46 areheld or locked in mechanically latched engagement with the upper end ofthe latching leg 440 in the slot 46a by means of magnetic force which issupplied from permanent magnet means mounted on the bight portion 44b ofthe U-shaped latch lever 44. As best shown in FIG. 5, the permanentmagnet holding force is established by a bar magnet 60 and a pair ofNorth and South, L-shaped pole pieces 62 and 64 which are attached by anonmagnetic rivet 66 to the latch lever 44. The L-shaped pole pieces 62and 64 are formed of soft iron material which is readily magnetized, andeach includes an elongated leg in contact with one face of the barmagnet 60 which is sandwiched between the legs. The outer end faces ofthe short legs of the pole pieces 62 and 64 lie on a common plane andare adapted to contact opposite end portions of a platelike soft ironcore member 68 which is secured to the base member 32 by a pair ofnonmagnetic rivets 72, or the like.

As shown in FIG. 5, the pole piece 62 is magnetized by the permanentmagnet 60 and becomes a north pole having a pole face labeled N which isattracted to the adjacent surface of the core 68, which also becomesmagnetized by the influence of the permanent magnet 60. The pole piece64 becomes a south pole having a pole face labeled S which is mutuallyattracted to the core 68 and a completed magnetic circuit is thusprovided to hold and maintain or lock the levers 44 and 46 (which may beconstructed of nonmagnetic material) in mechanically latched engagementagainst the biasing force of the spring 56 which exerts force tending topivot the lever 46 into the unlatched position. The magnetic attractionbetween the platelike core member 68 and the respective pole pieces 62and 64 set up by the permanent magnet 60 is sufficient to overcome theunlatching force exerted by the spring 56, and is also of sufficientstrength to overcome the force of gravity acting on the latch levers aswell as normal inertial forces developed because of acceleration anddeceleration of the aircraft. It is significant to note that an openingpull exerted on the upper edge of the door 30 in the direction of thearrow B in FIG. 1 is resisted by the mechanical engagement between thelatching levers 44 and 46 and is not dependent on magnetic holdingforces. Moreover, because there is no requirement for the latch levers44 and 46 to be made of magnetic or magnetizable materials, a wide rangeof suitable materials can be used to provide the needed strength. Themagnetic flux path between the permanent magnet 60 and core 68 does notpass through the body of the latch lever 44 and is entirely independentthereof.

In order to manually latch or unlatch the mechanism 20, a thin knifeliketool 74 having a curved finger 74a projecting outwardly of the forwardend (FIG. 70 is inserted through the slot 30a in the door 30. As thetool 74 is thrust inwardly in the direction of the arrow C, the latchlever 46 is pivoted in a counterclockwise direction from the unlatchedposition (dotted lines FIG. 2) to the latched or horizontal position ofFIG. 7, and simultaneously the upper curved surface of the finger 74a ofthe tool engages a forward projection 44d on the latch lever 44 andpivots the lever in a clockwise direction until latched engagement isestablished between the upper end of the latch leg 44c and the slot 46a.As the latch lever 44 is pivoted in clockwise fashion from the unlatchedposition to the latched position (FIG. 7, dotted lines), an attractivemagnetic force develops between the pole pieces 62 and 64 and the core68. This force helps to move the lever 44 into the latched position andthereafter maintains or magnetically locks the levers 44 and 46 inlatched engagement. The finger 74a of the tool can also be used tounlatch the system by placing the finger on top of the projection 44dand pivoting the tool 44 in a clockwise fashion until the magneticattraction between the pole pieces 62 and 64 and the core '68 is nolonger sufficient to hold the levers together against the force of thespring 56. In this case, when the tool 74 is withdrawn from the slot30a, the spring 56 acts to move the lever 46 to the unlatched position(dotted lines FIG. 2). In order that a pencil or other availableimplement can be used for manual latching or unlatching in case of anemergency, the slot 30a in the door includes an enlarged rounded portion30b (FIG. 5) to accommodate a pencil, screwdriver, or other implement76. The forward face of the latching leg 44c above the projection 44d isformed with an indentation Me to receive the end of the implement formanipulating the latch lever 44 into or out of latched engagement. TheU-shaped latch lever 44 is formed with a pivot stop or pivot limitingheel 44f on the upper end of the leg 44a. Engagement of the heel44fagainst the base 32 (FIG. 7) limits the downward travel of theforward latching leg 440 to the position shown and thus permits readyengagement of the tool 74 or other im plement for latching the assembly.

In accordance with the present invention, automatic unlatching of thelatching system 20 to permit access to the interior of the compartment26 by the passengers is normally effected by electrical means, such as aswitch or the like, operated by the pilot in the cockpit.

For this purpose, an electromagnetic coil winding is mounted on the core68 and the base 32 is formed with an enlarged slot 32a in order toaccommodate the winding. The coil winding comprises a relatively largenumber of turns wound onto the core so as to provide a magnetic polarityopposite that of the permanent when this occurs the latch member 44 ispivoted about the pin 42 in a counterclockwise direction from thelatched position to the unlatched position releasing the latch lever 46so that the door may be opened. As long as the coil winding 80 isenergized, the system cannot be relatched; however, as soon as the coilis deenergized the soft iron core 68 may again be attracted by themagnetism of the pole pieces 62 and 64 under the influence of thepermanent magnet 60, and relatching is readily accomplished with thetool 74 or other implement.

The latching system 20 provides a reliable, safe system which isnormally unlatched by electrical energy and which provides positivemechanical engagement to hold the compartment door closed. The latchedengagement is maintained by permanent magnetic locking or holding forceswhich can be overcome either by electromagnetic forces in normaloperation or in case of electrical failure the system can be unlatchedmanually. The latch system does not depend upon magnetic force forholding the compartment door in a closed position and, accordingly, canbe used in a variety of different applications wherein greater, morepositive mechanical latching strength is required.

Referring now to FIGS. 8-12, therein is illustrated another embodimentof a latching assembly with magnetic locking constructed in accordancewith the features of the present invention and generally referred to bythe reference numeral 120. The latching assembly includes a firstlatching subassembly 122 which is mounted on the top wall 17 of thecompartment 26 and a second latching subassembly 128 which is mounted onthe inside surface of the compartment door 30 adjacent the upper edge.

The second latching subassembly comprises a base assembly 130 formed ofa flat washer 132 secured to the inside surface of the door 30 by spotwelding or suitable fasteners. A second washer 134 with with a raisedcentral portion is secured to the flat washer 132 to provide a recess136 (FIG. 8) in order to accommodate a disk 138 which is attached to theinner end of a support post or rod 140 which projects outwardly of theinside surface of the door 30 at substantially right angles thereto. Thespace or recess 136 is larger than the space occupied by the disk 138and headed inner end of the support post or rod 140, and the raisedwasher 134 is provided with a central aperture slightly larger than thediameter of the rod to permit some free play or angular movement of therod with respect to an axis or median line perpendicular to the doorsurface. The outer end of the rod 140 is headed over against a sphericallatch member or ball 142 which is secured in place adjacent the free,outer end of the rod by the heading operation. In order to maintain therod in a generally perpendicular attitude relative to the door 30, yetpermit some free play or angular movement of the outer end of the rodwithin reasonable limitation, a stabilizing spring 144 is coaxiallyaligned on the rod adjacent the inner end portion thereof. The spring144 is formed with a plurality of helical convolutions whichprogressively decrease in diameter from a maximum adjacent the washerbase 134 to a minimum outwardly thereof on the body of the rod midwaybetween the ends thereof. When the spherical latch member 142 at theouter end of the rod 140 is deflected from the normal position whereinthe rod is normal to the door 30, the spring 144 acts to restore orreturn the rod and ball to the normal or median position.

In accordance with the present invention, the first latching subassembly122 includes a socketlike assembly generally indicated as 150 andadapted to receive and latchingly engage the single spherical ball orenlargement 142 on the free outer end of the support post 140 of thelatching subassembly 128. The socketlike latching assembly 150 includesa cylindrical, hollow sleeve 152 open at both ends and having a radiallyinwardly extended flange 154 at the forward end which provides aretaining ring at the forward end of the sleeve. A coaxially aligned,frustoconically shaped guide surface is provided on the forward face ofthe flange 154 in order to aid in axially centering the spherical latchmember 142 as it is moved in an axial direction into the interior of thesocket assembly 150. The cylindrical sleeve 152 is supported from a pairof side flanges 156 disposed on opposite sides thereof and a pair ofribs 158 (FIG. 13) connect the sleeve to the flanges 156.

The rearward end of the sleeve 152 is partially closed by a cap member160 having a central aperture therein in order to accommodate theforward end portion of an elongated, axially movable latch plunger 162having an enlarged forward end portion 164 which is mounted to slidewithin the sleeve. The rearward end portion of the latch plungerincludes a reduced diameter neck 162a and a sleeve 167 is mountedadjacent the outer end of the neck to act as a grommet or bushing duringreciprocal sliding movement of the plunger in a supporting aperture 170aformed in an upstanding rear flange 170 of a support bracket for thesubassembly 122. The enlarged forward end portion 164 of the slidablelatch plunger 162 is movable between a forward or latched position asshown in FIGS. 8 and 11 to a rearward or unlatched position shown inFIGS. and 12 wherein latching engagement with the ball 142 of thelatching subassembly 128 is released. The latching plunger 162 is biasedtoward the rearward or unlatched position by means of a coil spring 172disposed between the rear end closure wall 160 on the sleeve 152 and across pin 174 (FIG. 8) extended transversely through the body of theplunger 162.

In accordance with the present invention, the enlarged forward endportion 164 of the latching plunger 162 is formed with a deep axialrecess or counterbore 1640 which provides space for receiving andaccommodating the spherical latch ball 142 of the latching subassembly128 when the latching subassemblies 122 and 128 are in engaged latchedposition, as best shown in FIG. 8. A second, more shallow recess orcounterbore 164b of larger diameter is formed in the enlarged headportion 164 on the plunger 162, and a frustoconical outer surface 1640is formed to extend outwardly and forwardly of the second counterbore1641).

In order to provide mechanical latching engagement for holding andretaining the spherical ball 142 in latched engagement with the latchingsubassembly 122, a plurality of spherical latch balls 166 are mounted incircumferentially spaced array within the sleeve 152. Each of the latchballs 166 is formed with a diametrically disposed drilled passage 166atherethrough in order that a spring-steel C-ring 168 may be extended orthreaded therethrough. The C-ring 168 is constructed of spring wire andhas a nominal diameter when unstressed, as shown in FIG. 12, whichdiameter is considerably larger than its diameter in a compressed orstressed condition, as shown in FIG. 11. When the enlarged head portion164 of the latching plunger 162 is moved into the forward or latchedposition (FIG. 8), the latching balls 166 are forced by thefrustoconical surface 1640 into the counterbore 164b, which is smallerin diameter than the interior bore of the sleeve 152. When this occurs,the balls 166 are moved radially inwardly and the C-ring 168 iscompressed to provide latching engagement between the ring of balls 166of subassembly 122 and the single ball latch 142 of the latchingsubassembly 128. In this condition, a low friction mechanical latchedengagement is established between the spherical ball surfaces forholding the door 30 in the closed position.

In order to unlatch the latching assembly 120, the plunger 162 is movedrearwardly to the unlatched position as shown in FIG. 10, and theenlarged head portion 164 is shifted to the rear end of the sleeve 152.When this occurs, any outward pull on the ball 142 and expansion of theC-spring 168 to its normal unstressed position moves the balls 166radially outwardly and out of engagement with the single latch ball 142,as shown in FIG. 12. When this occurs, the door 30 may be freely openedand pivoted to provide immediate access to the interior of thecompartment 26. Latching mechanical engagement between the latchingsubassemblies 122 and 128 is maintained by tangential contact betweenthe spherical surfaces of the single ball 142 of the latchingsubassembly 128 and a plurality of balls 166 contained in the socketforming sleeve 152 of the latching subassembly 122. Because of thisarrangement, exactly accurate alignment between the subassemblies 122and 128 is not a necessity and close manufacturing tolerances of theindividual assemblies are not required. The mechanical holding abilityof the latching assembly 120, however, is not impaired even though closetolerances are not required.

The spring 172 biases the latch plunger 162 to the rear or the unlatchedposition and, in accordance with the present invention, the plunger isnormally main tained in the forward or latched position by means of apermanent magnet member 176 which is sandwiched between the longer legs,respectively, of a pair of L- shaped north and south pole pieces 178 and180 as best shown in FIG. 13. The pole pieces are made of soft ironwhich is readily magnetized by the permanent magnet 176 and thepermanent magnet and the pole pieces are mounted as a unit on anonmagnetic sleeve or grommet 181 which is carried on the reduceddiameter neck portion 162a at the rear end of the plunger 162 (FIG. 8).

As shown in FIG. 13, the north pole piece 178 includes a short leghaving an end face in a common plane, with the end face of the short legof the south pole piece 180. The aligned end faces of the respectivenorth and south pole pieces are adapted to contact and exert magneticattraction on a pair of fixed pole members 182 and 184 (FIG. 13),respectively, which are mounted at opposite ends of a flat core member186 (FIG. 8) of an electromagnetic coil 190. Rivets 188 or othersuitable fastening means (FIGS. 8 and 13) are provided to secure thecore 186 and the pole pieces 182 and 184 together. These members areformed of soft iron or other material which is readily magnetizable butdoes not retain permanent magnetism to any extent.

The coil winding 190 and circuitry connected thereto are polarized sothat when electric current is supplied to the coil the pole piece 182becomes a north pole and pole piece 184 becomes a south pole. With thispolarity, the electromagnetize pole pieces 182 and 184 and the permanentmagnet pole pieces 178 and 180 repel each other causing the plunger 162to shift to the rear and unlatch the mechanism.

When no current is supplied to the electromagnetic coil 190, the core186 and pole pieces 182 and 184 are magnetized by the permanent magnet176 acting through the L-shaped pole members 178 and 180. Attractiveforces are developed between pole members 182 and 184 and the polepieces 178 and 180 so that a completed series magnetic holding circuitis established through the members 176, 178, 180, 182, 184, and 186 forholding the latch plunger 162 in the forward or latched position againstthe force of the bias spring 172. It should be remembered, however, thatit is the mechanical latching engagement between the ball 142 and ringof balls 166 which provides the mechanical latching for holding the door130 in the closed position, and this mechanical force is many timesgreater than the magnetic holding or locking force between the pairs ofpole pieces 178 and 180 and 182 and 184. The latching assembly 120 thusprovides a system having mechanical latching with magnetic locking orholding for maintaining the latch assembly in the engaged or latchedposition.

In normal operation, when it is desired to unlatch the assembly 120 sothat the door 30 can be opened, electric current is supplied to the coilwinding 190 causing the core 186 to be magnetized and the pole pieces182 and 184 to become electromgnetized as north and south poles,respectively. When this occurs, magnetic repelling forces are developedbetween the pairs of poles 182 and 178 and the pairs 184 and 180. Theserepelling forcesovercome or replace the permanent magnet holding forceand shift the plunger 162 and head portion 164 rearwardly within thesocket or sleeve 152 from the latched position of FIG. 8 to theunlatched position shown in FIG. 10. When this occurs, the ring or arrayof latching balls 166 is free to shift radially outwardly as theC-shaped spring 168 expands. Latching engagement between the balls 166and the single latch ball 142 of the latching subassembly 128 is thenreleased, permitting the door 30 to be opened freely, as shown in FIG.10. Because of the socket and ball latching arrangement, close alignmentbetween the latching subassemblies 122 and 128 is not a necessitybecause the frustoconical guide surface on the forward face of theflange 154 of the socket guidies the ball 142 and support stem intoaxial alignment with the socket sleeve 152 as the door is closed. Afterthe door has been closed and the ball 142 is centered with the deepcounterbores 164a and 164b in the head portion 164, the latch plunger162 is shifted forwardly against the force of the bias spring 172 untilthe attractive magnetic forces developed by the permanent magnet 176between the pole pieces 178 and and the adjacent pole members 182 and184 are sufficient to hold and retain the flanges in latched engagementas shown in FIG. 8. This attractive retaining force is large enough toovercome the biasing force of the spring 172 and the force of the spring168, and as the head portion 164 shifts forwardly in the sleeve 152 theballs 166 are cammed inwardly by the conical surface 1640 into thecounterbore 164b. The surface of the counterbore l64b acts as acontainment surface preventing radially outward travel of the balls 166.The balls 166 are thus maintained in contact against the ball 142 andprevent the door 30 from being opened.

Manual unlatching of the assembly 120 is accomplished by a pull ring 192accessible through an opening 15a in the rear wall 15 of compartment 26.The pull ring 192 is pivotally connected to the sleeve 167 on the rearend of the latch plunger 162 and is readily grasped by the finger andmoved rearwardly to mechanically unlatch the assembly when desired, orif the electrical system fails. By manually moving the pole pieces 178and 180 far enough rearwardly to diminish the magnetic attractive forcebetween these pole pieces and their counterparts 182 and 184, the forceof the spring 172 is then available to hold the plunger 162 in theunlatched position until it is relatched. When it is desired to relatchthe latching system 120, the door 30 is closed so that the rod 140 andball 142 of the latching subassembly 128 is positioned in centeredalignment in the socket sleeve 152. The plunger 162 is moved forwardlyagainst the bias of the spring 172 until the magnetic pole pieces 178and 180, which are magnetized by the permanent magnet 176, exertsufficient magnetic attraction on the pole members 182 and 184 todrawthe plunger 162 forwardly into the latched position. The latchingassembly 120 is maintained in the latched position of FIG. 8 until it isunlatched either by electromagnetic energy supplied by energizing thecoil or by manually moving the plunger 162 rearwardly as by pulling onthe ring 192. The latching assembly 120 thus provides a low cost,extremely reliable latching system for use with an aircraft oxygencompartment.

Referring now to FIG. '13, a different type of manual unlatchingmechanism is provided, which includes an L-shaped lever 196 pivotallymounted on a pin 198. One leg of the lever is attached to the pin 174 onthe plunger 162 and the forwardly extending leg of the lever terminatesapproximately even with the front face of the door 30. The forward endof the forward leg of the lever 196 is accessible through an opening 30aformed in the door 30 so that the lever maay be moved to manuallyunlatch or latch the latching assembly 120.

Although the present invention has been described with reference toseveral illustrative embodiments thereof, it should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art that will fall within the spirit and scope of theprinciples of this invention.

What is claimed as new and desired to be secured by letters Patent ofthe United States is:

l. A latching assembly for a door swingable toward and away from adoorjamb, said latching assembly comprising a pair of mechanicallyengageable latch means mounted on said door and jamb, respectively, andmovable relatively between an engaged, latched position and adisengaged, unlatched position, permanent magnet means for retainingmechanically latched engagement between said pair of said latch means insaid latched position, electromagnet means having a polarity whileenergized opposing said permanent mag net means for overcoming theretaining force thereof permitting relative movement between said pairof said latch means to said unlatched position so that said door can beopened, one of said pair of said latch means including a pair ofrelatively movable members, said permanent magnet means mounted on oneof said members and said electromagnet means mounted on the other ofsaid members.

2. The latch assembly of claim 1 wherein said holding force exerted bysaid permanent magnet means extends in a direction generally normal tothe direction of movement of said door toward and away from saiddoorjamb.

3. The latch assembly of claim 1 wherein one of said latch members ismounted for pivotal movement relative to the other, said permanentmagnet means providing magnetic force for normally biasing saidpivotally mounted latch member toward said latched position to engagesaid other latch means until said force is overcome by opposing magneticforce developed by energization of said electromagnet means.

4. The latch assembly of claim 3 wherein said pivotally mounted latchmember includes stop means engageable with said other member forlimiting the pivotal movement away from said latched position.

5. The latch assembly of claim 1 wherein the other of said latch meansincludes an elongated stem supported at one end in cantilever fashionand an enlargement mounted adjacent the outer free end of said stem forlatching engagement with said one latch means in said latched position.

6. The latch assembly of claim 5 wherein said enlargement comprises aspherical ball mounted on said stem, said stem being laterally flexibleadjacent said outer free end and movable axially relative to said onelatch means into and out of latching engagement therewith.

7. The latch assembly of claim 6 wherein said one latch means comprisessocket forming means including a plurality of circumferentially spacedlatching balls movable radially of the axis of said stem into and out oflatching engagement with said enlargement on said stem and means formoving said balls into and out of latching engagement with saidenlargement.

8. The latching assembly of claim 7 wherein said one latch meansincludes a hollow sleeve for containing said balls and an elongatedplunger mounted for axial sliding movement relative to said sleevepermitting radial movement of said balls in response to the axialposition thereof, said permanent magnet means normally urging saidplunger into an axial position wherein said balls are in said latchedposition.

9. The latching assembly of claim 8 wherein the force exerted by saidelectromagnet means while energized is active to move said plunger intoa second axial position permitting said balls to move radially outwardout of latched engagement with said enlargement.

10. The latch assembly of claim 9 wherein magnetic force attractionbetween said permanent magnet means and said latch means is in adirection generally parallel of said plunger.

11. The latching assembly of claim 1 including manually actuated meansfor moving said one member against the holding force of said permanentmagnet means toward said unlatched position.

12. The latching assembly of claim 1 including manually actuatedunlatching means acting on said one member of said one pair of latchmeans carrying said permanent magnet means for moving said one memberrelative to the other member of said pair toward said unlatchedposition.

13. The latch assembly of claim 1 including spring means for biasingsaid one latch means away from said latched position.

1. A latching assembly for a door swingable toward and away from adoorjamb, said latching assembly comprising a pair of mechanicallyengageable latch means mounted on said door and jamb, respectively, andmovable relatively between an engaged, latched position and adisengaged, unlatched position, permanent magnet means for retainingmechanically latched engagement between said pair of said latch means insaid latched position, electromagnet means having a polarity whileenergized opposing said permanent magnet means for overcoming theretaining force thereof permitting relative movement between said pairof said latch means to said unlatched position so that said door can beopened, one of said pair of said latch means including a pair ofrelatively movable members, said permanent magnet means mounted on oneof said members and said electromagnet means mounted on the other ofsaid members.
 2. The latch assembly of claim 1 wherein said holdingforce exerted by said permanent magnet means extends in a directiongenerally normal to the direction of movement of said door toward andaway from said doorjamb.
 3. The latch assembly of claim 1 wherein one ofsaid latch members is mounted for pivotal movement relative to theother, said permanent magnet means providing magnetic force for normallybiasing said pivotally mounted latch member toward said latched positionto engage said other latch means until said force is overcome byopposing magnetic force developed by energization of said electromagnetmeans.
 4. The latch assembly of claim 3 wherein said pivotally mountedlatch member includes stop means engageable with said other member forlimiting the pivotal movement away from said latched position.
 5. Thelatch assembly of claim 1 wherein the other of said latch means includesan elongated stem supported at one end in cantilever fashion and anenlargement mounted adjacent the outer free end of said stem forlatching engagement with said one latch means in said latched position.6. The latch assembly of claim 5 wherein said enlargement comprises aspherical ball mounted on said stem, said stem being laterally flexibleadjacent said outer free end and movable axially relative to said onelatch means into and out of latching engagement therewith.
 7. The latchassembly of claim 6 wherein said one latch means comprises socketforming means including a plurality of circumferentially spaced latchingballs movable radially of the axis of said stem into and out of latchingengagement with said enlargement on said stem and means for moving saidballs into and out of latching engagement with said enlargement.
 8. Thelatching assembly of claim 7 wherein said one latch means includes ahollow sleeve for containing said balls and an elongated plunger mountedfor axial sliding movement relative to said sleeve permitting radialmovement of said balls in response to the axial position thereof, saidpermanent magnet means normally urging said plunger into an axialposition wherein said balls are in said latched position.
 9. Thelatching assembly of claim 8 wherein the force exerted by saidelectromagnet means while energized is active to move said plunger intoa second axial position permitting said balls to move radially outwardout of latched engagement with said enlargement.
 10. The latch assemblyof claim 9 wherein magnetic force attraction between said permanentmagnet means and said latch means is in a direction generally parallelof said plunger.
 11. The latching assembly of claim 1 including manuallyactuated means for moving said one member against the holding force ofsaid permanent magnet means toward said unlatched position.
 12. Thelatching assembly of claim 1 including manually actuated unlatchingmeans acting on said one member of said one pair of latch means carryingsaid permanent magnet means for moving said one member relative to theother member of said pair toward said unlatched position.
 13. The latchassembly of claim 1 including spring means for biasing said one latchmeans away from said latched position.